The long-term objective of this application is the development of a research program dealing with event-related potential (ERP) measures of information processing. The research described in this application is designed specifically to investigate event-related potential correlates of memory scanning when subjects are presented a dichotic task. Following a pilot investigation there will be two experiments. The objectives of the first study are to determine the influence of a single and dual-target auditory memory scanning task on the right-ear advantage (REA) and on the P300 component of he ERP and to uncover the relationship between the REA and the P300 component. The objective of the second study is to determine the differences in the REA and the P300 component associated with instructions designed to control the manner in which subjects deploy their attention during a single-target memory scanning task. In different conditions subjects will be instructed to attend to the syllables heard in the left ear, in the right ear, or in both ears. During both studies EEG activity from scalp locations at T3, C3, Cz, C4, and T4 as well as horizontal and vertical eye movement will be collected prior to and following the presentation of the auditory stimuli. Prior to averaging, all EEG activity will be processed by existing software to adjust for eye movement and for baseline and latency variability. Following data collection the REA measured in terms of detection accuracy and reaction time scores and the averaged amplitude and peak latency of the P300 component will be compared across all conditions and electrode placements within each experiment. Comparisons will also be made between P300 and REA indices. The results of this study have important implications for understanding the relationship between P300 and information processing both in normal and in clinical populations.